1. Field of the Invention
The present invention relates to integrated circuit packaging technology, and more particularly, to thermally enhanced integrated circuit packages.
2. Background Art
Integrated circuit (IC) chips or dies from semiconductor wafers are typically interfaced with other circuits using a package that can be attached to a printed circuit board (PCB). One such type of IC die package is a ball grid array (BGA) package. BGA packages provide for smaller footprints than many other package solutions available today. A BGA package has an array of solder ball pads located on a bottom external surface of a package substrate. Solder balls are attached to the solder ball pads. The solder balls are reflowed to attach the package to the PCB.
BGA packages are available in a variety of types. Example types of BGA packages include plastic BGA (PBGA) packages, flex BGA packages, ceramic BGA packages, fine pitch BGA (FPBGA or FBGA) packages, and wafer-level BGA (WLBGA) packages. In a typical BGA package, a chip is mounted to a substrate by a die attach material. In one type of package implementation, wirebonds electrically connect signals of the die to conductive features on the substrate. In another implementation, the die is flip-chip mounted to the substrate, and solder bumps are used to electrically connect signals of the die to conductive features on the substrate. An encapsulating material encapsulates the die, wirebonds (when present), and the top surface of the substrate. FBGA packages have solder balls that are smaller than those of other BGA package types, such as plastic, ceramic, and flex BGA packages, and a smaller ball pitch is used to space the solder balls.
Existing BGA packages are subject to high thermal stresses that result from the heat given off during operation of the mounted IC die. It is desirable to transfer the heat generated by the IC die from the package during operation to prevent damage to the package. Frequently, the material of the package substrate has very low values of thermal conductivity. Consequently, the IC die is typically separated from the PCB to which the package is mounted by the internal substrate thermal barrier. A large amount of research is being performed into relieving BGA package thermal stresses, and many BGA package configurations have been implemented over the years that attempt to remove excess package heat.
Millions of integrated circuit packages are needed each year to interface integrated circuit chips with devices. Thus, what are needed are improved packaging techniques that can help meet the high quantity production needs for integrated circuit packages, while addressing the need to produce packages that are efficient at removing excess heat.